Re: RE : Re: Complex recursion in XSLT 1.0

I agree to all your points. The functional nature of XPath is more
important than desiring a modifiable Stack.

I am sure, we can leverage the Stack implementation concept you gave
for practical applications.

On Thu, Feb 21, 2008 at 12:31 AM, Florent Georges <lists@xxxxxxxxxxxx> wrote:
> Mukul Gandhi wrote:
>
> > 1) On this line <!-- 2. --> , I create a variable
> > 'stack'. This is a new *variable* and not the old one (on
> > line <!-- 1. -->; because we cannot modify variables in
> > XSLT). This doesn't make me quite happy :)
>
>  Why?  I know you know the functional nature of XPath.
> Say you have a function that sums two numbers, would you
> expect that using it as in "x:add($v, 1)" the variable was
> modified?  Or just that the result of the addition to be
> returned as the value of the function?
>
>  Dealing with stacks or whatever is not different.  Values
> are not modifiable.  But you can build new value, possibly
> refering to other one.  And you can bind values to
> variables.  You can't modify stacks themselves.  But from
> existing stacks, you can builds new one with for instance
> the first value dropped, or with an extra value in front.
>
> > 2) On line <!-- 6. -->, I do x:top(x:pop($stack)). This
> > modifies a transient stack, and doesn't modify the
> > variable $stack.
>
>  Well, regarding the spec, a new sequence is created as the
> value of the function pop with param $stack.  This is the
> value of the function remove with params $stack and 1.  This
> value is then used by the function top to build a new value
> (a sequence of one or zero item, the first of the param).
>
>  The sequence bound to $stack is not modified.  And neither
> the intermediate sequences are (well, the observable
> behaviour is that no sequence can not be modified).
>
> > I would like the variable $stack to be modified. But
> > that's not possible, we know :)
>
>  Are you really sure you want that ?-)
>
> > I guess, these limitations will prohibit some stack
> > specific programs to be built.
>
> > Can we think of some strategies to overcome these
> > limitations.
>
>  I wonder what is a limitation for something called a stack
> and that allows you to push items, pop them and look at its
> top :-)
>
>
>  Regards,
>
> --drkm



-- 
Regards,
Mukul Gandhi